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matching a inverted char class with a char

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This commit is contained in:
Erik Krogh Kristensen
2020-10-31 18:14:10 +01:00
parent 804aaf36f0
commit 16473fc2a4
3 changed files with 32 additions and 10 deletions
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26
javascript/ql/src/Performance/ReDoS.ql
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@@ -429,6 +429,20 @@ newtype Trace =
t = Nil() and isFork(_, s1, s2, _, _)
}
/**
* Holds if the character class `cc` has a child (constant or range) that matches `char`.
*/
bindingset[char]
predicate charClassMatchesChar(RegExpCharacterClass cc, string char) {
exists(RegExpTerm child | child = cc.getAChild() |
char = child.(RegExpConstant).getValue()
or
exists(string lo, string hi | child.(RegExpCharacterRange).isRange(lo, hi) |
lo <= char and char <= hi
)
)
}
/**
* Gets a character that is represented by both `c` and `d`.
*/
@@ -437,14 +451,10 @@ string intersect(InputSymbol c, InputSymbol d) {
(
d = Char(result)
or
exists(RegExpCharacterClass cc | d = CharClass(cc) |
exists(RegExpTerm child | child = cc.getAChild() |
result = child.(RegExpConstant).getValue()
or
exists(string lo, string hi | child.(RegExpCharacterRange).isRange(lo, hi) |
lo <= result and result <= hi
)
)
exists(RegExpCharacterClass cc | d = CharClass(cc) | charClassMatchesChar(cc, result))
or
exists(RegExpCharacterClass cc | d = InvertedCharClass(cc) |
not charClassMatchesChar(cc, result)
)
or
d = Dot() and